Lens unit and imaging apparatus

ABSTRACT

A lens unit includes: a lens barrel; a movable section including a movable lens and configured to be moved in an optical axis direction relative to the lens barrel; a linear actuator configured to move the movable section in the optical axis direction; and a biasing blade spring including a holding portion for holding the movable section, a plurality of spring portions capable of being elastically deformed and biasing the movable section in the optical axis direction, and an attachment portion to be attached to the lens barrel. The plurality of spring portions of the biasing blade spring are configured to restraint a movement force produced at the movable section in a plane orthogonal to the optical axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens unit and an imaging apparatus.More specifically, the present invention relates to a lens unit having amovable section and an imaging apparatus including such a lens unit,which allows reduction of size and improvement of operation reliabilityof the movable section.

2. Description of the Related Art

A lens unit, which is constructed by disposing an imaging optical systemsuch as a movable lens in a lens barrel, is included in various types ofimaging apparatuses, such as a video camera and a still camera as wellas a mobile phone, etc. An example of such an imaging apparatus is onethat is equipped with a movable section having a movable lens forzooming or focusing, in which the movable section can be moved by alinear actuator in the optical axis direction (for example, see JapanesePatent 3387173 and Japanese Patent Application Publication H08-015593).

In such an imaging apparatus, the movable section is supported by a pairof guide shafts, to be movable in the optical axis direction. Themovable section is guided by the pair of guide shafts and moved in theoptical axis direction by way of drive power of the linear actuator.

SUMMARY OF THE INVENTION

In recent years, among such imaging apparatuses mentioned above,portable types become more popular. Accordingly, it is desirable tofurther reduce the size of such apparatuses.

However, the above-mentioned imaging apparatus has the guide shaft forguiding the movable section, which has a technical issue such that itrequire a space for accommodating the guide shaft, preventing fromachieving a further reduction of size.

Furthermore, there is provided a clearance of several microns forenabling movement of the movable section smoothly on the guide shaftsbetween the guide shaft and a bearing section. However, the clearancemay also allow minute lateral movement of the movable section and/orinclination of the movable section with respect to the optical axis.Such a lateral movement and inclination of the movable section may causedeterioration in quality of a captured image because an image focalpoint may deviate or a so-called image-shake phenomenon where an imagein the image focal plane may slightly shakes. Particularly, in portabledevices, the movement of the movable section within the plane orthogonalto the optical axis direction and the inclination to the optical axisare easy to occur due to changes in its orientation or vibrationsgenerated by various disturbances such as shock and shake applied to thedevices, etc.

Furthermore, when the movable section is moved in the optical axisdirection in a zoom lens, a focal lens, etc., the movable section needsto be held in a desired position, without producing any smalldisplacement in the optical axis direction.

Accordingly, it is desirable to realize reduction of size in a lens unitincluding a movable section and/or an imaging apparatus having such alens unit. Furthermore, it is desirable to improve reliability ofoperation of a movable section included in a lens unit and/or an imagingapparatus including such a lens unit. The present invention is conceivedin view of the above-described technical issues.

According to an embodiment of the present invention, there is provided alens unit and/or an imaging apparatus including such a lens unit. Thelens unit includes: a lens barrel in which an imaging optical system isdisposed; a movable section including a movable lens and configured tobe moved in an optical axis direction relative to the lens barrel; alinear actuator configured to move the movable section in the opticalaxis direction; and a biasing blade spring including a holding portionfor holding the movable section, a plurality of spring portions capableof being elastically deformed and biasing the movable section in theoptical axis direction, and an attachment portion to be attached to thelens barrel; wherein the plurality of spring portions of the biasingblade spring are configured to restraint a movement force produced atthe movable section in a plane orthogonal to the optical axis.

In another embodiment of the present invention, the movable section maybe formed to have a substantially circular outer shape when viewed alongthe optical axis direction; the lens barrel may be formed to have asubstantially rectangular outer shape when viewed along the optical axisdirection; and each of the spring portions of the biasing blade springmay be disposed at a respective one of four corners in the lens barrel.

In another embodiment of the present invention, each of the springportions may be formed into a form substantially equal to a letter “S”.

In another embodiment of the present invention, a pair of the biasingblade springs may be provided to be on opposite sides of the movablesection in the optical axis direction and spaced apart such that themovable section is positioned between the pair of biasing blade springs,the pair of biasing blade springs forcing the movable section such thatthe pair of the biasing blade springs approach to each other in theoptical axis direction.

In another embodiment of the present invention, the spring portions ofthe pair of biasing blade springs may be provided with line portionsrespectively extending in predetermined directions; and the pair of thebiasing blade springs may be configured such that the line portion ofone biasing blade spring and the line portion of the other biasing bladespring are perpendicular to each other.

In another embodiment of the present invention, the movable section maybe used as a movable section for focusing, the pair of biasing bladesprings may be configured to have different spring forces against themovable section; and the movable section may be positioned at aninfinite point by way of a biasing force of the biasing blade spring ifthe linear actuator is not in operation.

In the embodiments of the present invention, the movable section ismoved by way of drive power of the linear actuator in the optical axisdirection while the movable section is held by the biasing bladesprings.

Accordingly, the movable section may be moved in the optical axisdirection without causing the movable section to incline or deviate withrespect to the optical axis.

Furthermore, in the embodiments of the present invention, any guidingmeans, such as a guide shaft for guiding the movable section in theoptical axis direction is not required. Accordingly, it is possible toachieve reduction of size by simplifying mechanism of the lens unit andeliminating space for such guiding means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment in accordance with the present invention inconjunction with FIG. 2 through FIG. 26, and is a perspective viewshowing a mobile phone as an example of an imaging apparatus;

FIG. 2 is an enlarged plan view showing examples of two-dimensional barcodes;

FIG. 3 is an exploded perspective view of an imaging unit;

FIG. 4 is an exploded perspective view of an imaging unit which ispartially assembled;

FIG. 5 is an enlarged perspective view of an imaging unit;

FIG. 6 is a schematically enlarged sectional view of an imaging unitwhose movable section is held at an infinite position;

FIG. 7 is an enlarged and exploded perspective view of a lens barrel;

FIG. 8 is an enlarged perspective view showing a first member of thelens barrel when viewed from an angle that is different from that ofFIG. 7;

FIG. 9 is an enlarged perspective view showing a second member of thelens barrel when viewed from an angle that is different from that ofFIG. 7;

FIG. 10 is an enlarged perspective view of a first biasing blade spring;

FIG. 11 is an enlarged perspective view of a second biasing bladespring;

FIG. 12 is an enlarged perspective view showing a lens holder and a coilholder;

FIG. 13 is an enlarged rear view showing a structure where a secondbiasing blade spring is attached to a coil holder;

FIG. 14 is an enlarged perspective view showing a structure where afirst biasing blade spring and a second biasing blade spring areattached to a movable section;

FIG. 15 is an enlarged side view of an imaging unit before adhesion iscarried out;

FIG. 16 is a schematic view showing a spatial relationship of a springportion of a first biasing blade spring to a lens barrel and a movablesection;

FIG. 17 is a schematic view showing a spatial relationship of a springportion of a second biasing blade spring to a lens barrel and a movablesection;

FIG. 18 is a schematic enlarged sectional view showing an imaging unitwhere a movable section is held at a macro end;

FIG. 19 is a schematic representation showing force generated at eachportion such that an optical axis direction is in agreement with aperpendicular direction;

FIG. 20 shows a modification of a biasing blade spring in conjunctionwith FIG. 21 through FIG. 25, and is a schematic perspective viewshowing a biasing blade spring in accordance with a first modificationtogether with a movable section;

FIG. 21 is an enlarged front view showing a biasing blade spring inaccordance with a second modification;

FIG. 22 is an enlarged front view showing a portion of a biasing bladesprings in accordance with a third modification;

FIG. 23 is an enlarged front view showing a portion of a biasing bladesprings in accordance with a fourth modification;

FIG. 24 is an enlarged front view showing a portion of a biasing bladesprings in accordance with a fifth modification;

FIG. 25 is an enlarged front view showing a portion of a biasing bladesprings in accordance with a sixth modification; and

FIG. 26 is an enlarged sectional view showing an example of an imagingapparatus in which two lens units are provided.

DETAILED DESCRIPTION OF EMBODIMENTS

Below, embodiments of the present invention will be described withreference to the accompanying drawings. The present invention isapplicable to various types of imaging apparatuses, such as a mobilephone, a video camera, a still camera, etc., which have a function ofcapturing a video or a still image, or to various types of lens unitsused for these imaging apparatuses.

As an example of an imaging apparatus 1, there is provided a mobilephone as shown in FIG. 1. The imaging apparatus 1 is such that a firstcasing 2 and a second casing 3 are combined to form a foldable structurein conjunction with a hinge section 4.

The first casing 2 is provided with a speaker 5, a display section 6,and an antenna 7. This antenna 7 is configured to be extendable.

The second casing 3 is provided with various types of operating units 8,including a push button, a rotary dial, a microphone 9 and the like.

An imaging unit 10 is built into the hinge section 4. One of theoperating units 8, for example, a push button, may be preset to functionfor an image capture operation. By pressing and operating this operatingunit 8, the imaging unit 10 is operated to capture an image.

The imaging apparatus 1 also has a function to read out and identifyinformation such as various types of identification displays, which mayinclude a one-dimensional bar code, two-dimensional bar codes 1000 and2000 (see FIG. 2), etc. When images of these bar codes are captured bythe imaging unit 10, the code patterns are identified and informationbased on the identified code pattern is read out.

Next, an example of a structure of the imaging unit 10 is described. Itshould be noted that, for convenience, the description will be carriedout assuming that the optical axis direction (identified by S as shownin FIG. 3) is the forward/rearward direction and an object to be imagedis in the front side.

The imaging unit 10 is configured such that respective constitutingportions are disposed in a lens barrel 11, which is formed by a lensunit 10 a and an imaging section including an imager device (describedlater). The lens barrel 11 is configured such that a first member 12 anda second member 13 are sequentially combined (see FIG. 3 through FIG.6). The first member 12 and the second member 13 are formed of resinmaterial such as polycarbonate, etc.

As shown in FIGS. 7 and 8, the first member 12 is integrally formed witha base side section 14 facing forward and rearward, projections 15projecting rearward from right and left edges of the base side section14, and mating projections 16 projecting rearward from central portionsof the upper and lower edges of the base side section 14.

A shallow and annular receiving recess 17 is formed at a front side 14 aof the base side section 14 (see FIG. 7). A through hole 18 bored in theforward/rearward direction is formed in the central portion of the baseside section 14.

Ribs 19 projecting rearward are provided in positions around the throughhole 18 at a rear surface 14 b of the base side section 14 (see FIG. 8).The ribs 19 are formed in a circular form, and provided in acircumferential direction at regular intervals, and respectively havepedestals 19 a slightly projecting rearward on their rear surfaces. Whenthe movable section, as will be described later, is moved forward, thepedestals 19 a are allowed in contact with the movable section, and havea function to restrain forward movement of the movable section. Aposition where the movable section comes into contact with the pedestals19 a is considered as the macro end in a focusing operation.

It should be noted that in the imaging apparatus 1, as will be describedlater, by supplying a current to a drive coil, a linear actuator isdriven such that the movable section is moved from an infinite pointside to the macro end side. Alternatively, by controlling an amount ofthe current to be supplied, the movable section may be allowed to moveto in front of the position where it comes into contact with thepedestals 19 a, and such a front position may be set as the macro end,which is a front side of moving edge of the movable section.

The projections 15 of the first member 12 are respectively formed withthree vertically continuous sections, upper projections 20, middleprojections 21, and lower projections 22, in order from top to bottom(see FIGS. 7 and 8).

Concave positioning portions 20 a and 22 a, which open laterally andrearward, are formed on external surfaces of rear ends of the upperprojections 20 and rear ends of the lower projections 22, respectively(see FIG. 8).

An amount of rearward projection of one of the upper projections 20 andone of the lower projections 22 is larger than that of the other. Outeredges of such further projected portions are formed as spring receivingsurfaces 20 b.

Amounts of rearward projections of the middle projections 21 from thebase side section 14 are arranged to be smaller than amounts of rearwardprojections of the upper projections 20 and the lower projections 22from the base side section 14. In the middle projections 21, notchedportions 21 a which respectively open rearward are formed at centralportions with respect to the vertical direction.

The upper, lower, and both side ends of the rear surface 14 b of thebase side section 14 are formed as four spring holding surfaces 14 c(see FIG. 8). The spring holding surfaces 14 c are respectively locatedbetween the upper projections 20 and the mating projection 16 andbetween the lower projections 22 and the mating projection 16.

As shown in FIGS. 7 and 9, the second member 13 is integrally formedwith a base side portion 23 facing forward and rearward, projections 24each projecting rearward from the upper and lower sides of the base sideportion 23, and mating projections 25 each projecting rearward from thecentral portions of the right and left edges of the base side portion23.

A shallow and rectangular mounting recess 26 is formed at a back side 23a of the base side portion 23 (see FIG. 9). A light transmitting hole 27bored forward and rearward is formed in the central portion of the baseside portion 23. The back side 23 a of the base side portion 23 isprovided with positioning projections 28 projecting rearward,respectively at the four corners.

Ribs 29 projecting forward are provided in positions around the lighttransmitting hole 27 at a front side 23 b of the base side portion 23(see FIG. 7). Front sides of the ribs 29 are provided with pedestals 29a slightly projecting forward, in a circumferential direction of thelight transmitting hole 27 at separated positions. When the movablesection is moved rearward, the pedestals 29 a are contacted with themovable section and have a function to restrain rearward movement of themovable section. A position where the movable section comes into contactwith the pedestals 29 a serves as the infinite point for focusingoperation.

The front side 23 b of the base side portion 23 is provided, at itsright and left side ends, with positioning pins 30 spaced vertically(see FIG. 7). The sides, provided with the positioning pins 30 of thefront side 23 b of the base side portion 23 are formed as the springreceiving surfaces 23 c.

A right side 23 d of the base side portion 23 is provided with terminalmounting sections 31, which are spaced vertically.

The projections 24 of the second member 13 are provided as protrusions32 such that a portion closer to the left side end and a portion closerto the right side end further protrude forward out than other portions.End sides of the protrusions 32 are respectively formed as springholding surfaces 32 a (see FIG. 7).

Positioning projection 33 projecting forward are respectively providedin the position immediately below the upper protrusions 32 and in theposition immediately above the lower protrusions 32.

Notched portions 25 a which open rearward are formed at the matingprojections 25, respectively.

A cover glass 34 is attached, for example, by way of adhesion to thereceiving recess 17 which is formed at the front side 14 a of the firstmember 12 (see FIG. 3 through FIG. 5).

A first biasing blade spring 35 is attached to the lens barrel 11 (seeFIGS. 3 and 4).

The first biasing blade spring 35 is formed of a metal material which isrich in elasticity, such as beryllium copper, etc. The thicknessdirection of the first biasing blade spring 35 may be matched orsubstantially matched with the forward/rearward direction, i.e. theoptical axis direction. For example, the thickness is set to 0.07 mm. Asshown in FIG. 10, the first biasing blade spring 35 is integrally formedwith a holding portion 36, four spring portions 37, four attachmentportions 38, and connection portions ˜39.

The holding portion 36 is formed in a ring-shape.

The spring portion 37 is formed into a form substantially equal to aletter “S” lying horizontally, one end of which extends to a respectiveone of positions which are positioned at the same interval in thecircumference direction of the holding portion 36. The spring portion 37is formed with an inclined portion 37 a slightly projecting from theholding portion 36 in a radial direction, three parallel line portions37 b extending vertically, and arc-shaped curve portions 37 c whichinterconnect the adjacent line portions 37 b. An end of the line portion37 b located in the innermost portion is extended to an end of theinclined portion 37 a.

The attachment portions 38 are elongated in the right and leftdirection, and each outer end is extended to a respective one of ends ofthe line portions 37 b located in the outermost part.

The connection portions 39 are formed with horizontal portions 39 aextending in the right and left direction, and perpendicular portions 39b slightly extending vertically, in which one end of a respective one ofthe perpendicular sections extends to a respective one of right and leftends of the horizontal portions 39 a. The other end of each one of theperpendicular portions 39 b extends to an inner end of a respective oneof the attachment portions 38 The connection portions 39 are locatedsuch that the horizontal portions 39 a are closer to the holding portion36 than to the attachment portions 38.

Since the spring portions 37 are axisymmetric in the vertical directionand also axisymmetric in the left-right direction, the first biasingblade spring 35 is configured such that each of the spring portions 37provides the same spring force.

In the first biasing blade spring 35, the spring portions 37 areelastically deformed in the forward/rearward bending direction.Accordingly, the holding portion 36 moves in the forward/rearwarddirection with respect to the attachment portions 38, i.e., in theoptical axis direction. Force produced during the movement in the planeorthogonal to the optical axis is refrained by the line portions 37 band the curve portions 37 c, thus allowing the holding portion 36 tomove only in the optical axis direction.

The first biasing blade spring 35 is attached to the lens barrel 11 suchthat the attachment portions 38 are respectively held by the springholding surfaces 14 c of the first member 12 and the spring holdingsurfaces 32 a of the second member 13.

When the first biasing blade spring 35 is not elastically deformed, thefirst biasing blade spring 35 is configured such that surfaces in thethickness direction of each one of the holding portion 36, the springportions 37, the attachment portions 38, and the connection portions 39are respectively positioned in the same planes. In other words, thefirst biasing blade spring 35 may be formed simply by processing aplate-like material, thus making manufacturing thereof easy.

The second biasing blade spring 40 is attached to the lens barrel 11(see FIGS. 3 and 4).

The second biasing blade spring 40 is formed of a metal material whichhas elasticity, such as beryllium copper, etc. The thickness directionof the second biasing blade spring 40 may be matched or substantiallymatched with the forward/rearward direction, i.e. the optical axisdirection, except for the connecting terminal portion to be describedlater. The thickness is set to 0.05 mm, for example. The second biasingblade spring 40 is formed with two spring members 41 having a shapeaxisymmetric in the vertical direction.

As shown in FIG. 11, the spring member 41 is integrally formed with aholding portion 42, two spring portions 43, two attachment portions 44,a connecting terminal portion 45, and a coil connecting portion 46.

The holding portion 42 is formed in a semi-ring shape.

The spring portion 43 is formed into a form substantially equal to aletter “S”, one end of which extends to a respective one of portionswhich are separated at the same interval in the circumference directionof the holding portion 42. The spring portion 43 is formed with aninclined section 43 a slightly projecting from the holding portion 42 ina radial direction, three parallel line portions 43 b extending in theright and left direction, and arc-shaped curve portions 43 c whichinterconnect the adjacent line portions 43 b. An end of the line portion43 b located in the innermost portion is extended to an end of theinclined section 43 a.

Each of the attachment portions 44 is extended to an end of a respectiveone of the line portions 43 b, one end of which is located in theoutermost position. Positioning holes 44 a are formed in the attachmentportions 44, respectively.

The connecting terminal portion 45 is extended to one attachment portion44 and bent by approximately 90 degrees to this attachment portion 44,and projects rearward.

The coil connecting portion 46 projects in the radial direction from acircumferentially central portion of the holding portion 42, and isprovided in the central portion between portions respectively connectingthe holding portion 42 and the spring portions 43.

Since the spring portions 43 are axisymmetric in the vertical directionand also axisymmetric in the left-right direction, the second biasingblade spring 40 is configured such that each of the spring portions 43may provide the same spring force.

In the second biasing blade spring 40, the spring portions 43 areelastically deformed in the forward/rearward bending direction so asthat the holding portion 42 moves in the forward/rearward direction withrespect to the attachment portions 44, i.e. in the optical axisdirection. Force produced during the movement in the plane orthogonal tothe optical axis is restrained by the line portions 43 b and the curvesections 43 c, thus allowing the holding portion 42 to move only in theoptical axis direction.

A thickness of the second biasing blade spring 40 is thinner than athickness of the first biasing blade spring 35, and a spring force ofthe first biasing blade spring 35 is larger than a spring force of thesecond biasing blade spring 40.

The second biasing blade spring 40 is attached to the lens barrel 11such that each of the positioning pins 30 of the second member 13 isinserted into respective one of the positioning holes 44 a formed at theattachment portions 44, and the attachment portions 44 are held by thefirst member 12 and the second member 13.

When the second biasing blade spring 40 is not being elasticallydeformed, the second biasing blade spring 40 is configured such thatsurfaces in the thickness direction of each one of the holding portions42, the spring portions 43, the attachment portions 44, and the coilconnection portions 46 are respectively positioned in the same planes.When the connecting terminal portions 45 of the second biasing bladespring 40 are not being bent by approximately 90 degrees with respect tothe attachment portions 44, surfaces in the thickness direction of eachof the connecting terminal portions 45 and surfaces in the thicknessdirection of each one of the attachment portion 44 are respectivelypositioned in the same planes. Accordingly, the second biasing bladespring 40 may be formed by simply processing a plate-like material, thusmaking manufacturing thereof easy.

A yoke 47 is provided inside the lens barrel 11 (see FIGS. 3, 4, and 6).The yoke 47 is formed of a magnetic metal material, and formed with abase 47 a formed in a ring, a perimeter portion 47 b projecting rearwardfrom a perimeter of this base 47 a, and an inner periphery portion 47 cprojecting rearward from an inner periphery of the base 47 a.

A drive magnet 48 is provided inside the yoke 47. The drive magnet 48 isformed with four portions 48 a formed in the same shape and the samesize, and is mounted in the yoke 47 such that each of the portions 48 ais in contact with the base 47 a and the perimeter portion 47 b of theyoke 47 (see FIG. 6).

A movable section 49 is arranged inside the lens barrel 11 in such a waythat the movable section 49 is allowed to move in the optical axisdirection. The movable section 49 has a lens holder 50, a drive coil 51,and a coil holder 52 (see FIGS. 3 and 4).

As shown in FIG. 12, the lens holder 50 is formed in a substantiallycylindrical shape, and is provided at its front end with a positioningring section 50 a. Holding ribs 50 b are provided in the positionscloser to the front end of a perimeter of the lens holder 50 atregularly spaced intervals in a circumferential direction. Front edgesof the holding ribs 50 b are connected with a trailing edge of thepositioning ring section 50 a. Surfaces of the holding ribs 50 bconnecting to the trailing edge of the positioning ring section 50 a areformed as contact surfaces 50 c perpendicular to the optical axisdirection. A trailing edge of the lens holder 50 is provided with matingprojections 50 d, which are circumferentially spaced from each other.

A plurality of movable lenses which collectively function as a focallens, a lens block 53 which has a fixed iris diaphragm, etc. are mountedinside the lens holder 50 (see FIGS. 3 and 6).

The drive coil 51 is wound and formed into a ring, and its outerdiameter is smaller than an outer diameter of the drive magnet 48 (seeFIGS. 3, 4, and 6).

The coil holder 52 is thin and formed into a substantially ring-shape.Circumferentially spaced mating recesses 52 a are formed at an innerperiphery (see FIG. 12). A rear surface of the coil holder 52 isprovided with a positioning ring section 52 b (see FIG. 13). Both upperand lower ends of the coil holder 52 are respectively provided withprojections 52 c for coil winding, which are respectively projectedupward and downward.

The movable section 49 is configured such that the lens holder 50 towhich the drive coil 51 and the lens block 53 are attached is mounted tothe coil holder 52 (see FIGS. 3 and 14). The drive coil 51 is attachedto a perimeter portion at the front of the coil holder 52. Beingattached to the coil holder 52, each end is wound around a respectiveone of the coil winding projections 52 c of the coil holder 52 (seeFIGS. 13 and 14). The lens holder 50 is mounted to the coil holder 52 asthe mating projections 50 d are fitted into the mating recesses 52 a,respectively.

The movable section 49 is held by the holding portion 36 of the firstbiasing blade spring 35 and the holding portions 42 of the secondbiasing blade spring 40 (see FIG. 14).

As shown in FIG. 14, the holding portion 36 of the first biasing bladespring 35 is fitted onto the positioning ring section 50 a and broughtinto abutted to the contact surfaces 50 c of the holding ribs 50 b, thusbeing attached to the lens holder 50. As shown in FIG. 13, the holdingportions 42 of the second biasing blade spring 40 are fitted onto thepositioning ring section 52 b and brought into abutted to the rearsurface of the coil holder 52, thus being attached to this coil holder52.

When the second biasing blade spring 40 is attached to the coil holder52, as shown in FIGS. 13 and 14, the coil connecting portions 46 of thesecond biasing blade spring 40 are respectively adjacent to the coilwinding projections 52 c of the coil holder 52. Each end of the drivecoil 51 which is wound around a respective one of the coil windingprojections 52 c is connected to a respective one of the coil connectingportions 46 by solder 58.

A shading sheet 59 and an imaging section 60 are attached to the secondmember 13 (see FIGS. 3 and 4).

The shading sheet 59 has a through hole 59 a in the central part, and isdisposed and attached at the mounting recess 26 formed at the back 23 aof the second member 13 (see FIG. 6).

The imaging section 60 is formed with an imager housing 61, a controlcircuit board 62, an imager device 63, and a cover 64.

A shallow recess 61 a opening forward is formed at the imager housing61, and the imager device 63 is arranged at this recess 61 a. Forexample, a CCD (Charge Coupled Device) may be used as the imager device63.

The control circuit board 62 is a circuit board for controlling theimager device 63 and supplying a current to the drive coil 51. A rightend portion of the board is provided with connecting portions 62 a whichare vertically spaced and project forward (see FIGS. 3 and 4). Thecontrol circuit board 62 is attached to the rear surface of the imagerhousing 61, and the second member 13 of the control circuit board 62 ispositioned by positioning projections 28 which are provided for thesecond member 13, when the control circuit board 62 is attached to theimager housing 61.

The cover 64 is attached to the front of the imager housing 61, andprotects the imager device 63.

The imaging section 60 is attached to a rear surface 13 a of the secondmember 13 after the shading sheet 59 is attached.

Below, an assembling procedure for the imaging unit 10 will bedescribed.

First, the second biasing blade spring 40 is assembled to the secondmember 13. As described above, the assembly of the second biasing bladespring 40 to the second member 13 is carried out by respectivelyinserting the positioning pins 30 of the second member 13 into thepositioning holes 44 a, which are formed at the attachment portions 44of the respective spring members 41. At this time, the connectingterminal portions 45 of the second biasing blade spring 40 are disposedat the terminal mounting sections 31 of the second member 13,respectively.

Next, the movable section 49 is assembled to the second biasing bladespring 40. In a situation where the movable section 49 is assembled tothe second biasing blade spring 40, the movable section 49 is held bythe holding portions 42 of the second biasing blade spring 40, asdescribed above.

Subsequently, the yoke 47 to which the drive magnet 48 is attached isassembled to the second member 13. The yoke 47 is assembled such byfitting into the second member 13. The yoke 47 is positioned such thatits trailing end is in abutment with a predetermined portion inside thesecond member 13 (see FIG. 6). Having the yoke 47 mounted to the secondmember 13, the drive coil 51 is positioned between the inner peripheryportion 47 c of the yoke 47 and the drive magnet 48.

Accordingly, the linear actuator 65 is formed with the yoke 47, thedrive magnet 48, and the drive coil 51, by arranging the drive coil 51between the inner periphery portion 47 c of the yoke 47 and the drivemagnet 48 (see FIG. 6).

Next, the first biasing blade spring 35 is assembled to the movablesection 49. As described above, the assembly of the first biasing bladespring 35 to the movable section 49 is carried out by fitting theholding portion 36 onto the positioning ring section 50 a, and bringingit into abutment with the contact surfaces 50 c of the holding ribs 50 bHaving the first biasing blade spring 35 assembled to the movablesection 49, the attachment portions 38 of the first biasing blade spring35 are positioned on the spring holding surfaces 32 a which arerespective front ends of the protrusions 32 of the second member 13.

Subsequently, the first member 12 is assembled to the second member 13,combining the first member 12 and the second member 13. The assembly ofthe first member 12 to the second member 13 is carried out by insertingand fitting the positioning pins 30 of the second member 13 into thepositioning sections 20 a and 22 a of the first member 12, respectively.

As described above, the positioning pins 30 are inserted into thepositioning holes 44 a of the second biasing blade spring 40,respectively. Accordingly, the positioning pins 30 have a function ofcombining and positioning three members, which are the second biasingblade spring 40, the first member 12, and the second member 13.Accordingly, it is possible to improve accuracy of positioning thesecond biasing blade spring 40, the first member 12 and the secondmember 13, and to reduce the number of components by sharing thepositioning pins 30

In the example shown above, the second member 13 is provided with thepositioning pins 30, and the positioning sections 20 a and 22 a intowhich the positioning pins 30 are inserted are formed at the firstmember 12. Alternatively, the first member 12 may be provided withpositioning pins, and positioning sections into which the positioningpins are inserted may be formed at the second member 13. In this case,for example, the positioning holes into which the positioning pins areinserted may be formed in the first biasing blade spring 35 withoutforming the positioning holes. 44 a in the second biasing blade spring40.

After the first member 12 and the second member 13 are combined, oneprojection 24 of the second member 13 may be inserted between the upperends of the projections 15 of the first member 12, and the otherprojection 24 of the second member 13 may be inserted between the lowerends of the projections 15 of the first member 12, whereby theprojections 15 and 24 form a square tube-shaped portion.

Accordingly, the lens barrel 11 is easy to assemble, and the movablesection 49 whose outer shape is substantially circular or round whenviewed along the optical axis direction is constructed to be enclosed inthe box-like lens barrel 11, so as that the imaging unit 10 includingthe lens unit 10 a may be made in a smaller size. Furthermore, since thelens barrel 11 is formed into the box-shaped structure which is formedwith the base side sections 14, 23 and the projections 15, 24, it ispossible to realize a structure having less gaps or clearance, thuspreventing dirt from entering into inside the lens barrel 11.

As mentioned above, when the first member 12 and the second member 13are combined, the attachment portions 38 of the first biasing bladespring 35 are sandwiched and held by the spring holding surfaces 14 c ofthe first member 12 and the spring holding surfaces 32 a of the secondmember 13. Simultaneously, the attachment portions 44 of the secondbiasing blade spring 40 are pressed against the spring receivingsurfaces 23 c of the second member 13, and held by the spring receivingsurfaces 20 b and 22 b of the upper projections 20 and the lowerprojections 22 of the first member 12.

Thus, the attachment portions 38 of the first biasing blade spring 35and the attachment portions 44 of the second biasing blade spring 40 areheld by the first member 12 and the second member 13, and therefore aprocess, such as adhesion, is not particularly necessary in order toattach the first biasing blade spring 35 and the second biasing bladespring 40 to the lens barrel 11. Accordingly it is possible to improveflexibility of operation in a process of assembling the imaging unit 10including the lens unit 10 a.

Furthermore, since the attachment portions 38 of the first biasing bladespring 35 are held and fixed by the base side section 14 of the firstmember 12 and the projections 24 of the second member 13, and since theattachment portions 44 of the second biasing blade spring 40 are heldand fixed by the base side portion 23 of the second member 13 and theprojections 15 of the first member 12, the fixing positions (withrespect to the lens barrel 11) of the first biasing blade spring 35 andthe second biasing blade spring 40 are different and orthogonal to eachother, whereby the first biasing blade spring 35 and the second biasingblade spring 40 can be attached easily, without making the first member12 and the second member 13 into a complicated structure.

Next, the cover glass 34 is attached to the first member 12, and theshading sheet 59 and the imaging section 60 are attached to the secondmember 13. It should be noted that the attachment of the cover glass 34to the first member 12 may be carried out, before assembling the firstbiasing blade spring 35, the second biasing blade spring 40, the movablesection 49, etc.

Next, the connecting portions 62 a of the imaging section 60 attached tothe second member 13 are respectively connected with the connectingterminal portions 45 of the second biasing blade spring 40 by way ofsoldering or the like.

After the first member 12 and the second member 13 are combined and thelens barrel 11 is formed, the mating projections 16 of the first member12 are inserted and fitted between the protrusions 32 of the secondmember 13 (see FIG. 5).

The mating projections 25 of the second member 13 are respectivelyinserted and fitted between the upper projections 20 of the first member12 and the lower projections 22, while front ends of the matingprojections 25 are located apart from the front end of the middleprojections 21 (see FIG. 15). Accordingly, a cross-shaped opening whichcommunicates with the inside of the lens barrel 11 is formed among themating projections 25 and the middle projections 21. T his openingserves as adhesion holes 66. The perimeter portion 47 b of the yoke 47is located in the position corresponding to the adhesion holes 66 (seeFIG. 6).

Furthermore, when the first member 12 and the second member 13 arecombined, a predetermined space 67 is formed between the rear surface 14b of the base side section 14 of the first member 12 and the base 47 aof the yoke 47. This space 67 communicates with the adhesion holes 66(see FIG. 6).

Adhesives 68 are injected and applied to the adhesion holes 66 formed atthe lens barrel 11. The adhesives 68 may be ultraviolet curing typeadhesives, for example.

The adhesives 68 applied to the adhesion holes 66 penetrate through theadhesion holes 66 and into the space 67 formed between rear surface 14 bof the base side section 14 and base 47 a of the yoke 47. As theadhesives 68 in the adhesion holes 66 are hardened, three members, whichare the first member 12, the second member 13 and the yoke 47, areadhered together (see FIG. 6). Further, the first member 12 and the yoke47 are adhered together as the adhesives 68 are cured in the space 67.

As described above, in the lens unit 10 a, it is configured such thatthree members of the first member 12, the second member 13 and the yoke47 are adhered together by the adhesives 68 applied to the adhesionholes 66, and the first member 12 and the yoke 47 are adhered togetherby the adhesives 68 penetrated into the space 67. Accordingly, bondingstrength among the first member 12, the second member 13 and the yoke 47is high, and anti-vibration performance and drop-and-impact strength maybe improved.

Further, the adhesion holes 66 are formed into a cross-shape,respectively, thus leading to improvement in bonding strength.

Alternatively, an epoxy resin adhesive may be used as the adhesives 68.However, when the epoxy resin adhesive is used, there is a drawback.Although a two part adhesive has a high cure rate, its management istroublesome. There is also a drawback with a one part adhesive. Althoughits management is easy, its cure rate is low. As mentioned above,therefore, by using the ultraviolet curing adhesive as the adhesives 68,it is possible to facilitate the management of the adhesive and shortenan adhesion process. Especially, when the epoxy resin adhesive is used,it needs the cure time of 30 minutes or more. However, the ultravioletcuring adhesive needs the cure time of from 5 seconds to 30 seconds,which considerably shortens the time required for the process ofassembling the imaging unit 10 including the lens unit 10 a.

Further, when a one-part thermosetting epoxy-resin adhesive is used, itmay lead to problems such that not only the cure time is longer but alsoa dedicated heat treat furnace is needed. Accordingly, the manufacturecost may be higher, and the heat treatment may cause the lens to beeccentric, etc. However, it is possible to avoid these problems by usingthe ultraviolet curing adhesives as the adhesives 68.

In general, it is known that an ultraviolet curing adhesive has smallerbonding strength with a metal compared with that of a resin. However, itis possible to fix the yoke 47 firmly to the lens barrel 11 since theadhesive 68 allow the adhesion between the first member 12 and thesecond member 13 which are both formed of the resin material in additionto the adhesion between the yoke 47 formed of a metal material and thefirst member 12 and the second member 13 formed of a resin material, asdescribed above.

In the lens unit 10 a, since the positioning sections 20 a, 22 a formedin the upper projections 20 and the lower projections 22 of the firstmember 12 are each arranged to have concaved-shape and open to thelateral direction, the positioning pins 30 inserted into the positioningsections 20 a, 22 a are exposed outside. Accordingly, after combiningthe first member 12 and the second member 13, it is possible to carryout the adhesion at the combined portions respectively between thepositioning sections 20 a, 22 a and the positioning pins 30 As describedabove, by carrying out the adhesion at the combined portionsrespectively between the positioning sections 20 a, 22 a and thepositioning pins 30, it is possible to firmly fix the first member 12and the second member 13 together.

As described above, the assembly of the imaging unit 10 is completed bycombining and adhering the first member 12 with the second member 13.

As described above, the assembly of the imaging unit 10 may be carriedout such that the shading sheet 59 and the imaging section 60 areattached to the second member 13, and the second biasing blade spring40, the movable section 49, the yoke 47 to which the drive magnet 48 ismounted, the first biasing blade spring 35, and the first member 12 areassembled to the second member 13 in order of mention. Accordingly, theassembling work of the imaging unit 10 containing lens unit 10 a may beeasily performed, thus enabling to reduce work hours.

In the imaging unit 10 thus assembled, the lens barrel 11 has asubstantially rectangular shape and the movable section 49 has asubstantially circular shape when viewed along the optical axisdirection (see FIGS. 16 and 17). In this situation, the spring portions37 of the first biasing blade spring 35 and the spring portions 43 ofthe second biasing blade spring 40 are located at the four cornerswithin the lens barrel 11.

Accordingly, the spring portions 37 and 43 need the minimum arrangementspace, thus enabling to achieve reduction of size of the imaging unit 10including the lens unit 10 a.

In the imaging unit 10 thus assembled, the spring force of the firstbiasing blade spring 35 is larger than the spring force of the secondbiasing blade spring 40, as described above. Accordingly, when thelinear actuator 65 is not in operation where the drive coil 51 is notsupplied with the current, the movable section 49 is biased by way ofbiasing force of the first biasing blade spring 35 toward the imagingsection 60 side (back) in the optical axis direction, and the coilholder 52 is brought into contact with the pedestals 29 a of the secondmember 13, and is held at the infinite point when focusing, as shown inFIG. 6. In this infinite point, the first biasing blade spring 35 isarranged such that the holding portion 36 is located in front of theattachment portions 38, and the second biasing blade spring 40 isarranged such that the holding portions 42 are located behind theattachment portions 44

It should be noted that, in order to eliminate influences of a pixelpitch or sensitivity of lens and locate the movable section 49 at theinfinite point, the imaging section 60 may be adjusted by moving it in aforward/rearward direction with respect to the second member 13 whilethe coil holder 52 is in contact with the pedestals 29 a of the secondmember 13.

It is generally often the case that a user of the imaging apparatus 1uses the apparatus 1 in a situation where the movable section 49 is atthe infinite point rather than the macro end. Accordingly, as mentionedabove, by always holding the movable section 49 in the infinite point byway of the biasing force of the first biasing blade spring 35 when thelinear actuator 65 is not in operation, no electric power is necessaryto reach to the infinite point, i.e. the frequently-used state, thusreducing the electric power consumption to a minimum.

If it is assumed that the movable section is held more at the macro endthan the infinite point, the spring force of the second biasing bladespring 40 may be made greater than the spring force of the first biasingblade spring 35. According to this configuration, the movable section 49may be always held at the macro end by way of the biasing force of thesecond biasing blade spring 40 when the linear actuator 65 is not inoperation, whereby enabling to reduce electric power consumption atwhich the user uses more often.

An example of use at the macro end of the imaging apparatus 1 may be acase when reading information on various displays for identifying aone-dimensional bar code, two-dimensional bar codes 1000 and 2000 asshown in FIG. 2, etc.

When using the imaging apparatus 1 as a portable device, an orientationchange may arise in the movable section 49, depending on the directionin which the imaging apparatus 1 is held. However, as for the infinitepoint which may be more frequently used as mentioned above, since themovable section 49 is pushed and held against the second member 13 byway of the biasing force of the first biasing blade spring 35, theorientation change in the movable section 49 is unlikely to take place,thus improving the quality of image.

In order to drive the linear actuator 65, the current is supplied to thedrive coil 51. This supplying of the current is carried out through thecontrol circuit board 62 of the imaging section 60 and the secondbiasing blade spring 40. In one example, the second biasing blade spring40 may also serve as current supplying means in addition to the role ofbiasing the movable section 49. Accordingly, no dedicated means isrequired in the lens unit 10 a in order to supply the current to thedrive coil 51, thus enabling to reduce the number of components.

When the current is supplied to the drive coil 51 in a predetermineddirection, the linear actuator 65 drives the movable section 49 toward atarget object to be imaged (to front side) in the optical axisdirection, to a position corresponding to a magnitude of voltage (seeFIG. 18). The movable section 49 may be moved up to the macro end wherethe lens holder 50 is brought into contact with the pedestals 19 a ofthe first member 12. In this macro end, the first biasing blade spring35 is arranged such that the holding portion 36 is located in front ofthe attachment portions 38, and the second biasing blade spring 40 isarranged such that the holding portions 42 are located behind theattachment portions 44 However, the amounts of deformation of the springportions 37, 43 change as the movable section 49 moves forward. Thepositions (in the optical axis direction) between the holding portion 36and the attachment portions 38 are spaced apart further, compared withthose in the infinite point, and the respective positions (in theoptical axis direction) between the holding portions 42 and theattachment portions 44 are brought closer together compared with thosein the infinite point.

When the current supply to the drive coil 51 is turned off, the movablesection 49 is moved rearward by way of the biasing force of the firstbiasing blade spring 35.

In the imaging apparatus 1 as mentioned above, by supplying the currentto the drive coil 51, the movable section 49 is moved toward the targetobject side (forward) in the optical axis direction, and by stopping thecurrent supply to the drive coil 51, the movable section 49 is movedtoward the imaging section 60 side (rearward) in the optical axisdirection. Accordingly, the current supply to the drive coil 51 may beonly in one direction, making it easy to control and enabling to savepower consumption during focusing operation.

In addition, the example is shown above in which the first biasing bladespring 35 and the second biasing blade spring 40 which are formed of thesame material, are made different in thickness so as that the springforce of the first biasing blade spring 35 is greater than the springforce of the second biasing blade spring 40 however, the method ofmaking the spring force of the first biasing blade spring 35 larger thanthe spring force of the second biasing blade spring 40 is not limited tosuch a method in which both springs are formed with the same materialbut different in thickness. Alternatively, various types of methods maybe used, such as changing materials to form springs, changing form andwidth of spring portion, etc.

As described above, in the lens unit 10 a, the movable section 49 isheld by the first biasing blade spring 35 and the second biasing bladespring 40. Movement force produced at the movable section 49 in theplane orthogonal to the optical axis is restrained by the line portions37 b and the curve sections 37 c of the spring portions 37 of the firstbiasing blade spring 35, as well as a movement force produced at themovable section 49 in the plane orthogonal to the optical axis is alsorestrained by the line portion 43 b and the curve sections 43 c of thespring portions 43 of the second biasing blade spring 40, whereby themovable section 49 may be moved in the optical axis direction withoutcausing inclination or shift with respect to the optical axis.

Further, since the lens unit 10 a of the embodiments does not requireguide means, such as a guide shaft for moving the movable section 49 inthe optical axis direction, it is possible to simplify its mechanism andto achieve the reduction in size by reducing space required forarrangement.

Furthermore, since the first biasing blade spring 35 and the secondbiasing blade spring 40 are located on opposite sides of the movablesection 49, apart from each other in the optical axis direction. Inother words, the movable section 49 is in between the biasing bladesprings. Furthermore, the movable section 49 is moved while being biasedrearward by the first biasing blade spring 35 and biased forward by thesecond biasing blade spring 40. Accordingly, the movable section 49 maybe moved to and held at a new position with high position accuracy.

Still further, since the spring portions 37, 43 of the first biasingblade spring 35 and the second biasing blade spring 40 are formed into ashape substantially equal to a letter “S”, respectively having the lineportions 37 b, 43 b and the curve portions 37 c, 43 c, the springportions 37, 43 may be increased in length within a small space.Accordingly, it is possible to ensure a sufficient amount of deformationin the spring portions 37, 43 for a movement stroke of the movablesection 49 while ensuring reduction in size of the imaging unit 10including the lens unit 10 a.

Furthermore, in the lens unit 10 a, the first biasing blade spring 35 isconfigured such that the line portions 37 b of the spring portions 37extend vertically, and the second biasing blade spring 40 are configuredto be rotated about the optical axis by 90 degrees with respect to thefirst biasing blade spring 35 such that the line portions 43 b of thespring portions 43 extend in the horizontal direction. Accordingly, themovement force produced at the movable section 49 in the planeorthogonal to the optical axis may be restrained efficiently.

Next, relationships between gravity produced in the movable section 49and the spring force of the first biasing blade spring 35 etc. will bedescribed (see FIG. 19).

As described above, since the imaging apparatus 1 may be used also as aportable device, its orientation may change depending on condition ofuse.

For example, as the optical axis direction is brought into agreementwith the perpendicular direction (vertical direction), the first biasingblade spring 35 having a strong spring force may be located below andthe second biasing blade spring 40 having a weak spring force may belocated above.

As shown in FIG. 19, also in this state, the movable section 49 isbiased by biasing force P1 of the first biasing blade spring 35 towardthe second biasing blade spring 40 side (upward), and the movablesection 49 is biased by biasing force P2 of the second biasing bladespring 40 toward the first biasing blade spring 35 side (downward).However, in the first biasing blade spring 35, the second biasing bladespring 40, and the movable section 49, perpendicular and downwardgravities G1, G2, and G3 are respectively produced, which are inagreement with the optical axis direction.

In such a situation, in the imaging apparatus 1, upward biasing force Psobtained by subtracting the biasing force P2 of the second biasing bladespring 40 from the biasing force P1 of the first biasing blade spring35, is set such that it is larger than the total of gravitiesGt(=G1+G2+G3). Accordingly, even if the drive coil 51 is not suppliedwith the current, the movable section 49 may be held reliably in theinfinite point regardless of the use condition of the imaging apparatus1 since the movable section 49 is always pushed against the moving edgeon the imaging section 60 side by means of the first biasing bladespring 35 irrespective of the orientation at which the imaging apparatus1 is used.

In addition, as the movable section 49 moves in the optical axisdirection, the biasing force Ps obtained by subtracting the biasingforce P2 of the second biasing blade spring 40 from the biasing force P1of the first-biasing blade spring 35 changes with the amount ofdeformation of the spring portions 37 of the first biasing blade spring35 and the spring portions 43 of the second biasing blade spring 40. Thebiasing force Ps may be set to, for example, twice the total of gravityGt when the movable section 49 is at the infinite point, t. The biasingforce Ps may be set to, for example, 5 times through 10 times the totalof gravity Gt when the movable section 49 is located at the macro end.

Below, modification of the biasing blade spring will be described (seeFIGS. 20 through 25). It should be noted that the first modification andthe second modification are each shown schematically in FIGS. 20 and 21.

As shown in FIG. 20, each of biasing blade springs 69 in accordance withthe first modification has a holding portion 69 a, spring portions 69 band an attachment portion 69 c. The spring portions 69 b are locateddiagonally with respect to the holding portions 69 a. Positions of thespring portions 69 b of one biasing blade spring 69 are respectivelyrotationally spaced apart by 90 degrees from positions of the springportions 69 b of the other biasing blade spring 69 in a direction ofrotation about the optical axis.

With a simple structure in which the biasing blade springs 69 asmentioned above are used, the movable section 49 may be moved in theoptical axis direction, without causing the movable section 49 toincline or shift with respect to the optical axis.

As shown in FIG. 21, the biasing blade spring 70 in accordance with thesecond modification has a holding portion 70 a, spring portions 70 b andan attachment portion 70 c. The spring portions 70 b are connected tothe holding portion 70 a at the same interval in the direction ofrotation about the optical axis.

By using the biasing blade spring 70 as mentioned above, the movablesection 49 may be moved in the optical axis direction, without causingthe movable section 49 to incline or shift with respect to the opticalaxis with a simple structure.

As shown in FIG. 22, a biasing blade spring 71 in accordance with thethird modification has a holding portion 71 a, a spring portion 71 b andan attachment portion 71 c, and the spring portion 71 b is formed in ashape of substantially rectangle.

As shown in FIG. 23, a biasing blade spring 72 in accordance with thefourth modification has a holding portion 72 a, a spring portion 72 band an attachment portion 72 c, and the spring portion 72 b is formedinto a form substantially equal to a letter “Z”.

As shown in FIG. 24, a biasing blade spring 73 in accordance with thefifth modification has a holding portion 73 a, a spring portion 73 b andan attachment portion 73 c, and the spring portion 73 b is formed into aform substantially equal to a letter “W”.

As shown in FIG. 25, a biasing blade spring 74 in accordance with thesixth modification has a holding portion 74 a, a spring portion 74 b andan attachment portion 74 c, and the spring portion 74 b is formedspirally.

By using the biasing blade springs 71, 72, 73, and 74 as mentionedabove, the movable section 49 may be moved in the optical axisdirection, without causing the movable section 49 to incline or shiftwith respect to the optical axis with a simple structure.

Furthermore, especially in the biasing blade spring 73 in accordancewith the fifth modification and the biasing blade spring 74 inaccordance with the sixth modification, lengths of the spring portions73 b and 74 b may be lengthened within small spaces, thus achievingreduction in size of the imaging unit 10 including the lens unit 10 aand increase the amounts of deformation of the spring portions 73 b and74 b.

It should be noted that in the biasing blade springs 69 in accordancewith the first above-mentioned modification and the biasing blade spring70 in accordance with the second modification, the spring portions 69 b,70 b are schematically shown in FIGS. 20 and 21. However, shapes of thespring portions 69 b, 70 b may have a form substantially equal to aletter “S” like the first biasing blade spring 35 and the second biasingblade spring 40. Further, it is possible to use any of a rectangle, aletter “Z”, a letter “W”, a spiral shape and any form substantiallysimilar to any of the previous forms or shapes, as in the biasing bladespring 71 in accordance with the third modification through the biasingblade spring 74 in accordance with the sixth modification.

Further, the above-mentioned shapes of respective spring portions aremerely examples, and their shapes are not limited thereto, and a springportion of any shape may be employed, provided it acts as a blade springand has a shape allowing biasing force against the movable section 49.

Although examples are shown above in which the lens unit 10 a employsfocal drive, the lens unit 10 a may also employ zooming drive.

Further, as shown in FIG. 26, the embodiments of the present inventionmay also be used for an imaging apparatus 1A which performs focal driveand zooming drive. An example of such an imaging apparatus 1A will bedescribed in the following:

The imaging apparatus 1A has the lens units 10 a provided within anouter lens barrel 75. The lens unit 10 a disposed at the front side isfor zooming, and the lens unit 10 a disposed at the rear side is forfocusing. The imaging section 60 is provided at the rear end of theouter lens barrel 75.

A first lens 76 is mounted to the front end of the outer lens barrel 75as a first lens group, and a second lens 77 is mounted inside the outerlens barrel 75 as a third lens group. The second lens 77 is disposedbetween the lens units 10 a. Accordingly, each movable lens of themovable section 49 of the lens unit 10 a on the front side functions asa second lens group, and each movable lens of the movable section 49 ofthe lens unit 10 a on the rear side functions as a fourth lens group.

In such an imaging apparatus 1A, by driving the linear actuator 65 ofthe lens unit 10 a to the front side, the movable section 49 is moved inthe optical axis direction while being held with the first biasing bladespring 35 and the second biasing blade spring 40, thereby carrying out azooming operation. By driving the linear actuator 65 of the lens unit 10a to the rear side, the movable section 49 is moved in the optical axisdirection while being held with the first biasing blade spring 35 andthe second biasing blade spring 40, thereby carrying out a focusingoperation.

The imaging apparatus 1A does not require guide means, such as a guideshaft. Accordingly, mechanism of the imaging apparatus 1A may besimplified and the arrangement space therein may be reduced, to therebyachieve reduction in size. Further, since the respective movablesections 49 are held with the first biasing blade springs 35 and thesecond biasing blade springs 40, the movable sections 49 may be moved inthe optical axis direction, without causing the movable sections 49 toincline or shift with respect to the optical axis.

It should be noted that the vertical, forward/rearward directions asshown above are used for convenience of description, but notexclusively.

In the embodiment described above, the movable section is formed to havea substantially circular outer shape when viewed along the optical axisdirection, the lens barrel is formed to have a substantially rectangularouter shape when viewed along the optical axis direction, and each ofspring portions of the biasing blade spring is located at a respectiveone of four corners in the lens barrel. Accordingly, the spring portionsonly require the minimum arrangement space, and the lens unit may beminiaturized.

In the embodiment described above, each spring portion of the biasingblade spring is formed into a form substantially equal to a letter “S”.Accordingly, larger length of the spring portion may be secured withinsmall space, thus achieving reduction of size of the lens unit whileensuring a sufficient amount of deformation of the spring portion for amovement stroke of the movable section.

In the embodiment described above, a pair of the biasing blade springsare provided to be on opposite sides of the movable section in theoptical axis direction and spaced apart such that the movable section isplaced between the biasing blade springs, and the pair of biasing bladesprings are arranged so as to bias the movable section in such a waythat the pair of biasing blade springs approach each other in theoptical axis direction. Accordingly, the movable section may be held ata new position after movement with high position accuracy.

In the embodiment described above, the spring portions of the pair ofbiasing blade springs are provided with line portions respectivelyextending in predetermined directions, and the pair of the biasing bladesprings are configured such that the line portion of one biasing bladespring and the line portion of the other biasing blade spring areperpendicular to each other. Accordingly, any force produced at themovable section in the plane perpendicular to the optical axis may berestrained efficiently.

In the embodiment described above, the movable section is used as amovable section for focusing, the pair of biasing blade springs areconfigured to have different spring forces against the movable section,and the movable section is positioned at the infinite point by way ofthe biasing force of the biasing blade spring when the linear actuatoris not in operation. Accordingly, it is possible to bring the lens unitto a frequently-used status (the infinite position) without consumingany electric power, thereby enabling to reduce the power consumption toa minimum.

The present invention claims priority to its priority document No.2005-037972 filed in the Japanese Patent Office on Feb. 15, 2005, theentire contents of which being incorporated by reference herein.

The particular shapes and structures of each portion as shown in theabove-mentioned embodiments are merely examples of the embodimentperformed when implementing the present invention, and the technicalscope of the present invention is not construed exclusively by them.

1. A lens unit comprising: a lens barrel in which an imaging opticalsystem is disposed; a movable section including a movable lens andconfigured to be moved in an optical axis direction relative to the lensbarrel; a linear actuator configured to move the movable section in theoptical axis direction; and a biasing blade spring including a holdingportion for holding the movable section, a plurality of spring portionscapable of being elastically deformed and biasing the movable section inthe optical axis direction, and an attachment portion to be attached tothe lens barrel; wherein the plurality of spring portions of the biasingblade spring are configured to restraint a movement force produced atthe movable section in a plane orthogonal to the optical axis.
 2. Thelens unit according to claim 1, wherein: the movable section is formedto have a substantially circular outer shape when viewed along theoptical axis direction; the lens barrel is formed to have asubstantially rectangular outer shape when viewed along the optical axisdirection; and each of the spring portions of the biasing blade springis disposed at a respective one of four corners in the lens barrel. 3.The lens unit according to claim 1, wherein: each of the spring portionsis formed into a form substantially equal to a letter “S”.
 4. The lensunit according to claim 1, wherein: a pair of the biasing blade springsare provided to be on opposite sides of the movable section in theoptical axis direction and spaced apart such that the movable section ispositioned between the pair of biasing blade springs, the pair ofbiasing blade springs forcing the movable section such that the pair ofthe biasing blade springs approach to each other in the optical axisdirection.
 5. The lens unit according to claim 4, wherein: the springportions of the pair of biasing blade springs are provided with lineportions respectively extending in predetermined directions; and thepair of the biasing blade springs are configured such that the lineportion of one biasing blade spring and the line portion of the otherbiasing blade spring are perpendicular to each other.
 6. The lens unitaccording to claim 4, wherein: the movable section is used as a movablesection for focusing, the pair of biasing blade springs are configuredto have different spring forces against the movable section; and themovable section is positioned at an infinite point by way of a biasingforce of the biasing blade spring if the linear actuator is not inoperation.
 7. An imaging apparatus having an imager device and a lensunit in which an imaging optical system is provided in a lens barrel,the lens unit comprising: a movable section including a movable lens andconfigured to be moved in an optical axis direction relative to the lensbarrel; a linear actuator configured to move the movable section in theoptical axis direction; and a biasing blade spring including a holdingportion for holding the movable section, a plurality of spring portionscapable of being elastically deformed and biasing the movable section inthe optical axis direction, and an attachment portion to be attached tothe lens barrel; wherein the plurality of spring portions of the biasingblade spring are configured to restraint a movement force produced atthe movable section in a plane orthogonal to the optical axis.
 8. Theimaging apparatus according to claim 7, wherein: the movable section isformed to have a substantially circular outer shape when viewed alongthe optical axis direction; the lens barrel is formed to have asubstantially rectangular outer shape when viewed along the optical axisdirection; and each of spring portions of the biasing blade spring islocated at a respective one of four corners in the lens barrel.
 9. Theimaging apparatus according to claim 7, wherein: each of the springportions of the biasing blade spring is formed into a form substantiallyequal to a letter “S”.
 10. The imaging apparatus according to claim 7,wherein: a pair of the biasing blade springs are provided to be onopposite sides of the movable section in the optical axis direction andspaced apart such that the movable section is positioned between thepair of biasing blade springs, the pair of biasing blade springs forcingthe movable section such that the pair of the biasing blade springsapproach to each other in the optical axis direction.
 11. The imagingapparatus according to claim 10, wherein: the spring portions of thepair of biasing blade springs are provided with line portionsrespectively extending in predetermined directions; and the pair of thebiasing blade springs are configured such that the line portion of onebiasing blade spring and the line portion of the other biasing bladespring are perpendicular to each other.
 12. The imaging apparatusaccording to claim 10, wherein: the movable section is used as a movablesection for focusing, the pair of biasing blade springs are configuredto have different spring forces against the movable section; and themovable section is positioned at an infinite point by way of a biasingforce of the biasing blade spring if the linear actuator is not inoperation.